The Youngest Planet to Have a Spin-Orbit Alignment Measurement AU Mic b

Addison, Brett C. ORCID: https://orcid.org/0000-0003-3216-0626 and Horner, Jonathan and Wittenmyer, Robert A. and Heitzmann, Alexis and Plavchan, Peter and Wright, Duncan J. ORCID: https://orcid.org/0000-0001-7294-5386 and Nicholson, Belinda A. and Marshall, Jonathan P. and Clark, Jake T. and Gunther, Maximilian N. and Kane, Stephen R. and Hirano, Teruyuki and Wang, Songhu and Kielkopf, John and Shporer, Avi and Tinney, C. G. and Zhang, Hui and Ballard, Sarah and Bedding, Timothy and Bowler, Brendan P. and Mengel, Matthew W. ORCID: https://orcid.org/0000-0002-7830-6822 and Okumura, Jack and Gaidos, Eric and Wang, Xian-Yu (2021) The Youngest Planet to Have a Spin-Orbit Alignment Measurement AU Mic b. The Astronomical Journal, 162 (4):137. pp. 1-12. ISSN 0004-6256

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Abstract

We report measurements of the sky-projected spin-orbit angle for AU Mic b, a Neptune-size planet orbiting a very young (similar to 20 Myr) nearby pre-main-sequence M-dwarf star, which also hosts a bright, edge-on, debris disk. The planet was recently discovered from preliminary analysis of radial-velocity observations and confirmed to be transiting its host star from photometric data from the NASA's TESS mission. We obtained radial-velocity measurements of AU Mic over the course of two partially observable transits and one full transit of planet b from high-resolution spectroscopic observations made with the Minerva-Australis telescope array. Only a marginal detection of the Rossiter-McLaughlin effect signal was obtained from the radial velocities, in part due to AU Mic being an extremely active star and the lack of full transit coverage plus sufficient out-of-transit baseline. As such, a precise determination of the obliquity for AU Mic b is not possible in this study and we find a sky-projected spin-orbit angle of lambda=47(-54)(+26)degrees. This result is consistent with both the planet's orbit being aligned or highly misaligned with the spin axis of its host star. Our measurement independently agrees with, but is far less precise than observations carried out on other instruments around the same time that measure a low-obliquity orbit for the planet. AU Mic is the youngest exoplanetary system for which the projected spin-orbit angle has been measured, making it a key data point in the study of the formation and migration of exoplanets-particularly given that the system is also host to a bright debris disk.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Date Deposited: 12 Jan 2022 01:12
Last Modified: 10 Sep 2022 22:05
Uncontrolled Keywords: Exoplanets; Hot Neptunes; Exoplanet astronomy; Radial velocity; Exoplanet detection methods; Dynamical evolution; 498; 754; 486; 1332; 489; 421; Astrophysics - Earth and Planetary Astrophysics; Astrophysics; - Solar and Stellar Astrophysics
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Identification Number or DOI: https://doi.org/10.3847/1538-3881/ac1685
URI: http://eprints.usq.edu.au/id/eprint/44805

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